Updated protobufs for new authentication modules in client

Changed Authentication to contain a required string username and a list of AuthenticationEntry protobufs
Added AuthenticationEntry, contains a required string key and a required byte[] value
Also updated .gitignore to ignore IDEA project files

Change-Id: I9cb4a272c9e29f6fd156c0be8744df6770381d34
Session handling update

Added "sessionToken" field to the Protobuf to support session handling

Change-Id: I79929370e209f9e8117d8a154595ef55ed32b2e9
Session handling update 3

Removed AuthenticationEntry and Authentication protobufs, added
AuthRequest and AuthResponse protobufs with optional fields for
sending and receiving auth data. JSON is no longer used in the
Response "message" field for sending auth response data.

Change-Id: If92237592fd968539fe041cc2c7c4eae866f1826
Performance instrumentation update 1

Added Ping message to protocol.
Co-commits: svmp-android-client, android_external_svmp_eventserver

Change-Id: I0263af98bebbd077c759d6b9193e0e17bfdf6c5a
Auth module update 1

Separated Auth Types from Auth Modules; now supports any
combination of Auth Modules.

Change-Id: I97b5700fab61db17762c694ba367b687a814e3dd